The developers of optical sorting systems which are uniquely adapted for visually inspecting a mass-flow of a given food product have endeavored, through the years, to provide increasing levels of information which are useful in making well-informed sorting decisions to effect sorting operations in mass-flow food sorting devices. While the capturing and processing of product images employing prior art cameras and other optical devices has long been known, it has also been recognized that images of a product formed by visible spectrum electromagnetic radiation typically will not provide enough information for an automated sorting machine to accurately identify all (and especially hidden) food or other agricultural defects, and which may subsequently be later identified after further processing of the product. For example, one of the defects in agricultural products which have troubled food processors through the years has been the effective identification of “sugar end” defects in potato products, and more specifically potato products that are destined for processing into food items such as French fries and the like.
“Sugar ends” and which are also referred to as “dark ends”, “glassy ends”, “translucent ends” and “jelly ends” is a physiological, tuber disorder, which is caused by environmental conditions which occur during the growth of the potato plant. Potato strips or fries made from “sugar end” potatoes exhibit or display undesirable dark-brown areas on the product after it has been subjected to frying. This defect is typically caused by the higher concentration of reducing sugars found in the given darkened region of the potato. The process of frying the product results in caramelizing, which creates the undesirable dark brown region on the fried product. Heretofore, the challenge with food processors has been that the “sugar end” defects are typically invisible to traditional optical detection technology until after the potato product has been thoroughly fried. In view of this situation, potato strip processors can be unaware they have “sugar end” problems with a given lot of potatoes they are processing until their downstream food service customers fry the potato strips and then provide complaints. “Sugar ends” are usually associated with tubers that have a harvested shape which are somewhat pointed on the stem end of the potato. However, tubers having what is considered to be an ideal shape may also develop this anomaly.
Those skilled in the art have recognized that cultural, or management practices that increase a potato plant's susceptibility to heat or moisture stress during tuber initiation, and bulking, can encourage “sugar end” development. As should be understood, tubers are particularly sensitive to environmental stress during the early bulking phase. It has been found that sugars can develop in tubers weeks or even months after environmental stress occurs.
Prior art attempts have been made to provide a means for detecting “sugar ends” in an optical sorting device. An example of one of these devices is seen in U.S. Patent Publication No. U.S. 2014/0056482A1 to Burgstaller et al. and which discloses a sensor unit in a machine for detecting “sugar end” defects of potatoes, and which includes a methodology which has the steps of irradiating potatoes with at least one light source and collecting a reflected light; and then applying at least one classification feature to the light measurement signals taken from the reflected light. In the methodology as described in that published application, the at least one classification feature corresponds to a predefined “sugar end” criterion. Once the respective potato being sorted is classified as having a “sugar end” defect it is, thereafter, removed from further processing. It should be understood that the means employed in this published application for the determination or detection of a classification feature comprises, at least in one form of the invention, calculating a deference curve for individual locus points by calculating the differences between the spectral light measurement signals of the respective locus points, and the spectral values of a referenced spectrum for a number of wavelengths; or by calculating the differences between the nth derivative of the spectral light measurement signals of the respective locus points, and the nth derivative of the reference spectrum for a number of wavelengths.
While this methodology, as discussed in the above-referenced published patent application has achieved some degree of success, the implementation of the methodology has proved, in some instances, to be difficult or cumbersome. Consequently, the amount of potato products which can be processed utilizing this same technology appears to be somewhat limited in view of the complexity of the methodology as more specifically outlined in that reference. The teachings of U.S. Patent Publication No. U.S. 2014/0056482A1 is incorporated by reference herein.
The present invention, as described hereinafter, avoids the detriments associated with the prior art practices, and provides a new method of sorting which allows food processors an improved means for detecting, and then removing agricultural products having defects in a manner not possible, heretofore.